Study On Pressure Wave Characteristics Of Underground Station Of Intercity Railway Under The Airport

With the improvement of the urbanization level in China,the urban agglomeration has gradually become an important carrier and form of supporting and driving urbanization,and therefore intercity railway has become the preferred mode of transportation among cities.Due to the increasing shortage of land for urban construction,there will be more intercity railway underground stations in the future.In addition,in order to achieve rapid connection and facilitate passenger transfer,a fast and efficient integrated transportation hub will be built by connecting the intercity railway underground station with airport terminals,urban rail transit stations,long-distance passenger stations,and other facilities.A tunnel pressure wave and train wind will be formed when the train passes through the underground station at high speed,with the propagation of which the passengers on board and the personnel in the tunnel will feel a series of pressure pulses.In addition,the tunnel pressure wave will also form additional transient loads on the exterior of the train and the surface of the equipment in the tunnel,thus affecting their structural strength.The train wind has strong turbulence characteristics and causes strong airflow.The disturbance of the train to the ambient air in the form of air pressure and flow will act on the personnel near the line threatening their safety and may roll up or blow away the objects on the platform,affecting the safety of the train.Besides,the wind applying pulsating wind pressure on buildings and equipment adjacent to the line may cause damage accidents.In order to ensure the safety of drivers,passengers,and equipment in the tunnel,it is necessary to study the aerodynamic characteristics of underground intercity railway trains,the results of which can provide a theoretical basis for the structural design of underground stations.This thesis is based on a specific project of an airport intercity railway project.This thesis studies the influence on the pressure variation at different positions of the tunnel and the station referring to the train speed,the stop in the arrival-departure station,the opening of the platform screen door on the side of the arrival-departure line,the setting of the separation wall in the throat area and the mainline tunnel.The numerical calculation model of the pressure wave in the underground station of the intercity railway is established by means of theoretical analysis,dynamic model test,and numerical simulation.And the numerical calculation method is verified by model test.The main research contents and conclusions are as follows:(1)The law of pressure variation in the tunnel and the station when the train crosses the underground station at a speed of 160 km/h and compares the influence of the train speed on the pressure change in the tunnel and the station is analyzed in this thesis.The results show that the compression wave generated by the train entering the tunnel and its propagation in the complex tunnel will be reflected at the sudden change of the tunnel section.The attenuation amplitude of the pressure wave after reflection is related to the clearance area at the section.The larger the clearance area at the section is,the smaller the attenuation amplitude of the pressure wave after reflection is.When the train enters the tunnel,the amplitude of the initial compression wave and expansion wave generated at the tunnel entrance is proportional to the square of the train’s running speed.The positive pressure amplitude appears when the front train passes the measuring point,while the negative one appears before the rear train passes the measuring point.(2)A comparative analysis is conducted on the pressure changes of the train passing through the underground station at a speed of 160 km/h when there is a train stop on the arrival-departure line,and the screen door on the arrival-departure line is opened and when there is no stop,and the screen door is closed.The results show that when there is a train stopped on the arrival-departure line,the opening of the screen door has an obvious slowing effect on the pressure wave amplitude in the throat area.The positive pressure extreme value decreased by 22.3% while the negative one decreased by 39.2%.The positive pressure extreme value on the surface of the screen door in the mainline station increased by 55.1%while the negative one decreased by 32.6%.(3)A comparative analysis is made on the pressure changes in the tunnel and the station when the train crosses the underground station at a speed of 160 km/h with or without a separation wall in the throat area and the main tunnel.The results show that the pressure on the surface of the train body increases obviously with the setting of the separation wall.The positive pressure amplitude at the train nose is increased by 437 Pa,the negative one at the rear is increased at 577 Pa,and the negative one at the midpoint of the car body is increased by 792 Pa.After the separation wall is installed,the pressure fluctuation range of the screen door surface in the mainline tunnel is significantly larger than that of the non-separation wall.The positive pressure extreme value increases by 421 Pa,and the negative value increases by736 Pa.